1. Technical Field
The present invention relates to vehicle wiper devices. In particular, the present invention relates to a vehicle wiper device equipped with a blade having a cleaning-liquid ejecting function.
2. Related Art
A vehicle wiper device is used as a device that cleans the surface of a vehicle windshield by wiping off rainwater and dirt therefrom. The vehicle wiper device is provided with a blade at a moving end of a pivot arm and reciprocates this blade on the surface of the windshield so as to wipe and clean the windshield.
Furthermore, in order to make the wiping-cleaning function more effective, a mechanism that feeds and ejects a cleaning liquid onto the surface of the windshield is also provided. In recent years, a configuration that ejects the cleaning liquid directly from the blade is used so as to eject the cleaning liquid to a more appropriate position or region of the windshield.
For example, Japanese Unexamined Patent Application Publication No. 05-97017 discloses a wiper blade having a structure that sprays the cleaning liquid toward the glass surface. According to this technique, a packing member normally provided to blade rubber serving as the blade body has a cleaning-liquid feed passage. Thus, it is not necessary to provide an additional tube or spray nozzle, thereby achieving a simplified structure as well as a facilitated manufacturing process.
In the case where the blade itself has a cleaning-liquid ejecting function as in the related art technology described above, the cleaning liquid can be ejected relatively uniformly and to appropriate positions over a wide range of the windshield. However, because the blade normally moves in a substantially circular pattern in a state where there is always a substantial amount of cleaning liquid in front of the blade in the moving direction thereof, the cleaning liquid tends to splatter outward in the radial direction of the moving region of the blade due to the effect of a centrifugal force generated as a result of the movement of the blade.
In particular, with regard to a blade (i.e., a second blade) having a moving region that includes a region below an upper mid region of the windshield, the cleaning liquid may become pushed out to the upper mid region of the windshield as the second blade moves. Then, the cleaning liquid pushed out to the upper mid region of the windshield can no longer be wiped off with the second blade.
Thus, until a blade (i.e., a first blade) with a moving region that includes the upper mid region of the windshield performs subsequent wiping operation, the cleaning liquid remains in the upper mid region. For ensuring good forward visibility, this state in which the cleaning liquid remains in the upper mid region of the windshield is not preferred since the cleaning liquid may subsequently drip downward and remain in the main region of the windshield.
Furthermore, in recent years, some vehicles are equipped with a function that captures an image of the conditions ahead and assists in driving based on the captured data. In such vehicles, since an image capturing device, such as a camera, is disposed in the upper mid region of the windshield, the state where the cleaning liquid remains therein may adversely affect the function of the image capturing device.
FIG. 5 illustrates a problem in a vehicle having image capturing devices, such as cameras, disposed in the upper mid region of a windshield 100. Specifically, FIG. 5 illustrates how a cleaning liquid 26 splattering from a reciprocating second blade 14 in the radial direction thereof (indicated by an arrow 220) enters a specific region 18 on the windshield 100, which is a region including the field angle of image capturing devices 16-1 and 16-2. In this state in which the cleaning liquid 26 remains in the specific region 18, the function of the image capturing devices 16-1 and 16-2 is adversely affected.
Therefore, in a blade having a cleaning-liquid ejecting function, there is a challenge to prevent the cleaning liquid from remaining in the upper mid region of the windshield as much as possible.